At the Percona engineering team, we often receive requests to analyze changes in MySQL/Percona Server for MySQL behavior from one version to another, either due to regression or a bug fix (when having to point out to a customer that commit X has fixed their issue and upgrading to a version including that fix will solve their problem).
In this blog post, we will analyze the approach used to fix PS-7019 – Correct query results for LEFT JOIN with GROUP BY.
Each release comes with a lot of changes. For example, the difference between MySQL 8.0.19 to 8.0.20:
git diff mysql-8.0.19..mysql-8.0.20 | wc -l 737454 git diff mysql-8.0.19..mysql-8.0.20 --name-only | wc -l 4495
737K lines in 4495 files have changed from one minor version to another.
git …[Read more]